Anti-inflammatory and analgesic activities of SKLJI, a highly purified and injectable herbal extract of lonicera japonica

Abstract

The parenteral route has many merits over the oral route, including greater predictability, reproducibility of absorption, and rapid drug action, but injectable phytomedicines are uncommon due to protein precipitating tannin and hemolytic saponin components. In this study, in an effort to develop a safe injectable analgesic phytomedicine, we prepared a tannin and saponin-free Lonicera japonica extract, SKLJI, through fractionation and column purification, and evaluated its anti-inflammatory and analgesic activities in in vivo experimental models of inflammation and pain. The removal of tannin and saponin resulted in loganin and sweroside-enriched SKLJI and it showed reduced hemolysis and protein precipitation. In efficacy tests, SKLJI inhibited croton oil-and arachidonic acidinduced ear edema, acetic acid-induced writhing, and carrageenan-induced rat hind paw hyperalgesia. Inhibition of cylcooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and 5-lipoxyfenase (5-LO) activities by SKLJI appeared to be the mechanism underlying anti-inflammatory and analgesic efficacy. Loganin and sweroside also showed anti-inflammatory and analgesic activities, suggesting that they might be active principles in the efficacy of SKLJI. These results suggest that SKLJI is a viable candidate for a new antiinflammatory and analgesic phytomedicine that can be administered by the parenteral route.